<p>This study investigates the effect of tungsten (W) on the nucleation of precipitates in Fe-22wt.%Cr-25wt.%Ni austenitic steel and its impact on mechanical and corrosion properties. Steels containing 1.5 wt.% and 2.5 wt.% W were subjected to long-term aging at 710&#xa0;°C for up to 3000 h. Microstructural characterization using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and x-ray diffraction (XRD) revealed that W influences phase evolution by refining M₂₃C₆ carbides and promoting the formation of W-containing Laves, NbC, Z, and L1₂ phases. Tensile and fracture analysis showed that the higher W content improved ductility, with a transition from brittle intergranular fracture to a mixed transgranular–intergranular mode. TEM analysis confirmed the presence of W-Laves and NbC phases, contributing to enhanced creep resistance. These findings highlight the role of W in optimizing the mechanical performance of Fe-22wt.%Cr-25wt.%Ni steel for high-temperature applications. Potentiodynamic polarization, impedance spectroscopy, and Mott–Schottky measurements were done at high temperature (80&#xa0;°C) in a 3.5% NaCl solution demonstrated that the steel with higher W exhibited lower current densities and a more stable passive film, improving corrosion resistance. These findings highlight the role of W in optimizing the mechanical and electrochemical performance of Fe-22wt.%Cr-25wt.%Ni steel for high-temperature applications.</p>